Drive system for conveyers



Sept. l22, 1953 T. B. .loci-IEM DRIVE SYSTEM FOR CONVEYERS 3 Sheets-Sheet l Filed Nov. 7 1949 Sept. 22, 1953 T. B. JocHEM DRIVE SYSTEM FOR CONVEYERS 5 Sheets-Sheet 2 Filed Nov. 7, 1949 I I. -1 IW |III|WMWII| il!! :Q H :Ev/.mmm ZZ H- VIII. n m m E. SL um @u lv ESE m u M21 mm www?. .n AHI IL MS E mw u ||I I p.. XV .um 53 .m M T m www IJlIL om 0 ma Y Rw w N@ @b .Wl\m o /mvg mv@ @Q O Il ||.HI||..|| ...A un .l Q r3 .11H i MI T Al @Q uw T mldd om u@ y@ mm\\ fl| @M VIK Sept. 22, 1953 T B. JocHEM DRIVE SYSTEM FOR coNvEyERs s Sheets-sheet 5 Filed Nov. '7, 1949 V Patented Sept. 22, 1953 DRIVE SYSTEM FOR coNvEYERs Theodore B. Jochem,

to Cutler-Hammer,

Wauwatosa, Wis., assigner Inc., corporation of Delaware Milwaukee, Wis., a.

Application November 7, 1949, Serial No. 125,866

6 Claims. l

This invention relates to conveyors and more particularly to a drive system for conveyors. In newspaper printing plants, double belt conveyors are commonly installed for effecting transport of a stream of finished papers from the press folder to a mail or delivery room. During operationof the press, such conveyors are usually driven by power derived from a shaft of the press folder which in turn derives its power from the press motor or motors. This type of conveyor drive is desirable because it insures that the conveyor will run in synchronism with the press which may be run at various speeds depending upon various factors, such as, the number of papers to be made up in a particular production run, the number of units feeding the folder, operating conditions, etc. To insure that any finished papers remaining in the press folder and conveyor will be run-out following shut down of the press and press folder, an auxiliary driving motor is usually provided to drive the conveyor and the fly belts leading from the press folder alone.

As will -be appreciated, a certain amount of driving power is required to drive an empty conveyor, the amount depending upon the length 'and complexity of the conveyor runs. During a production run of the press, the conveyor system will be loaded with papers throughout a greater portion of the run and such load requires additional driving power, such additional dri-ving power varying in relation to the weight of the individual papers. Experience has shown that in operating such conveyors by power derived from a kshaft of the press folder, such shaft should not be called upon to exert appreciably in excess of 650 pound-inches torque in affording drive of the ily belts of the press folder and the conveyor proper.

Because of the length and complexity of the conveyor system in certain installations and/or because of the usual Weight of the individual papers to be handled, more driving power is required to operate the conveyor system than can be safely obtained through a shaft of the pressI folder. It has heretofore been proposed that a booster motor or motors be provided to help drive the conveyor under such conditions. In order to maintain synchronization of the conveyor speed with that of the press throughout the range of operating speeds of the latter, this has necessitated the use of rather complex control systems so that the booster motors are kept in step with the press operating speed.

A primary object of the present invention is to provide a novel form of drive system for conveyors employing one or more booster motors of such character that the problem of synchronizingy the speed of such booster motors with the speed of the main conveyor drive is non-existent.

Another object is to provide a drive system of the aforementioned character which may be readily adapted to different conveyor layouts by mere addition or subtraction of the number of booster motors and motor starters therefor.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate one preferred embodiment of the invention which will now be described in detail, it being understood that the embodiment illustrated is susceptible of various modifications in respect of its details without departing from the scope of the appended claims.

In the drawings,

Figure 1 is a schematic showing in side elevation of a newspaper conveyor system.

Fig. 2 is a schematic showing in side elevation of a drive mechanism for the conveyor system shown in Fig. 1.

Fig. 3 graphically depicts an operating characteristc of certain motors shown in Fig. 2, and

Fig. 4 is a schematic and diagrammatic showing of a control system for the driving motors shown in Fig. 2.

kReferring to Fig. 1, it shows a typical conveyor system for a newspaper printing plant which is coordinated with the printing press to effect delivery of the finished papers as they leave the press to a delivery table located at some point remote from the press itself, such as in a mail room. Generally considered, the conveyor system comprises the y belts Ill of a press folder II, a double belt type conveyor having interconnecting sections I3, M, I5, I6, I'I, I8 and I9 and a delivery table 20. Press folder II may be considered as part of a printing press (not shown) and together with such press is afforded drive by the alternating current electric motor 2l or alternatively by a similar motor 22, which motors have a clutch coupling 23 therebetween. It may be assumed that for plating and threading of the press prior to the start of the production run that the clutch 23 is engaged and that the motor 22, usually of small rating compared to the motor 2 I, is energized to afford drive of the press at low speeds through the motor `2l which is deenergized. Further, it may be assumed that during a production run the clutch 23 is disengaged and the motor 2| is energized to afford drive of the press, press folder lI I, and through a drive mechanism to be hereinafter described, drive of fly belts Ill'and'all sections of the conveyor. In addition, a clearance motor 24 is provided to afford drive of the fly belts i and of the conveyor alone, following shut-down of the press and press folder II at the end of a production run, thus insuring that any papers remaining on the fly belts Iii and in the conveyor will be runout to the delivery table.

Conveyor section I3 terminates at one end within a press connection unit 25 and at its other end within a section joint 26 where it interconnects with one end of conveyor section I4. Conveyor section I4 terminates at its other end within a corner unit 21 where it interconnects at a right angle relation with one end of conveyor section I5. Conveyor section I5 at its other end terminates within a section joint 28 where it interconnects with one end of a conveyor section I6. The termination of conveyor section I6 at its other end is not shown, nor is the entering end of conveyor section I1 shown. It may be assumed that there may be other conveyor sections between conveyor sections I6 and I1, the number of such other conveyor sections depending upon the length of the horizontal traverse involved, and that such other conveyor sections in-v terconnect with conveyor sections I6 and I1 within section joints like section joint 28, Conveyor section I1 terminates within a corner unit 29 where it interconnects at a right angle relation with conveyor section I8. Conveyor section I8 at its other end terminates within a section joint 30 where it interconnects with one end of conveyor section I9. Conveyor section I9 at its other end terminates at delivery table 20.

Press connection unit constitute a built-up supporting framework affording support of shafts 3l and 32 on which are mounted the end pulleys for the endless belts of conveyor section I3. S-haft 32 also has mounted thereon the drive pulleys for transfer belts 33 which form an interconnection between the fly belts I0 and the belts of conveyor section I3. Unit 25 also supports a shaft 34 on which are mounted end pulleys for y belts I0, and, shafts 35 and 36 on which are mounted idler pulleys for transfer belts 33. As will be hereinafter explained, press connection unit 25 also affords support of certain parts of the drive mechanism.

Section joints 26, 28, 30 and corner units 21 and 29, may also be considered to constitute individual supporting frameworks affording support of shafts on which are mounted end pulleys for the belts of the interconnecting conveyor sections. More particularly, section joint 26 supports shafts 31 and 38 on which are mounted end pulleys for the belts of conveyor section I3 and end pulleys for the belts of conveyor I4. Corner unit 21 has mounted therein shafts 39 and 40 on which are supported end pulleys for the belts of conveyor section I4 and end pulleys for belts of conveyor section I5. Shaft 40 also has mounted thereon drive pulleys for corner belts 4I. Corner unit 21 further supports shafts 42 and 43 on which are mounted idler pulleys for corner belts 4 I.

Section joint 28 supports shafts 44 and 45 on which are mounted end pulleys of the belts of conveyor section I5 and end pulleys of the belts of conveyor section I6,

Corner unit 29 supports shafts 46 and 41 on which are mounted end pulleys for belts of conveyor section I1 and end pulleys for belts of conveyor section I8. Shaft 41 also `supports drive pulleys for corner belts 48. Corner unit 29 additionally supports shafts 49 and 50 on which are mounted idler pulleys for corner belts 48.

25 may be considered to g.

Section joint 30 supports shafts 5I and 52 on which are mounted end pulleys for the belts of conveyor section I8 and end pulleys for belts of conveyor section I9.

Delivery table has associated therewith an end unit 53 which may be assumed to constitute a built-up framework affording support of shafts and certain parts of the conveyor drive mechanism. More particularly, end unit 53 supports shafts 54 and 55 on which are mounted end pulleys for the belts of conveyor section I9. Shaft 54 also has mounted thereon drive pulleys for transfer belts 56. End unit 53 additionally supports shafts 51 and 58 on which are mounted idler pulleys for transfer belts 56.

Shafts 31 and 38 of section joint 26, shafts 39 and 40 of corner unit 21, shafts 44 and 45 of section joint 28, shafts 46 and 41 of corner unit 29, shafts 5I and 52 of section joint 30 and shafts 54 and 55 of end unit 53 have drive interconnections therebetween as depicted by the broken lines 59, 60, 6I, 62, 63 and 64. Such broken lines may be assumed to represent meshing gears of one to one ratio carried on the pairs of shafts which afford drive of the second mentioned shaft of each pair when the first mentioned shaft of each pair is driven as will be hereinafter explained in detail. Shaft 3l of press connection unit 25 has drive interconnections with shafts 32 and 34 as depicted by the broken lines 65 and a which may be assumed to represent a gear carried on shaft 3I, meshing with like gears car-v ried on shafts 32 and 34, thereby enabling drive of shafts 32 and 34 by drive of shaft 3| in a one to one ratio.

Referring to Fig. 2, it shows the main driving mechanism for the conveyor system shown in Fig. 1. Driving power is transmitted from a sprocket I-lb supported on a shaft Il in press folder Il by means of an endless chain 66 which runs on sprocket Ilb and on a sprocket 61 xed to one element of an over-running clutch 68 carried on a shaft 69 which is supported by press connection unit 25. Clearance motor 24 is connected to one element of an over-running clutch 1I) mounted in press connection unit 25 by means of ya Shaft 1I. The other element of clutch 'I9 carries a sprocket 12 on which runs an endless chain 13. Chain 13 also runs on a sprocket 14 fixed on shaft 3 I. Drive interconnection between shafts 3l and 69 is afforded by means of an endless chain 15 running on sprockets fixed on said shafts.

The drive mechanism thus far described is such that shaft 3l may be driven by power derived from the shaft IIa of press folder II or alternatively by clearance motor 24. When the press is in operation, chain 66 runs in the direction shown and clutch 68 is thus engaged affording drive of shaft 69 in the clockwise direction. Chain 15 is thus caused to run clockwise to drive shaft 3| in the same direction. Drive of shaft 3| in the clockwise direction causes chain 13 to run in the same direction, but clutch 10 over-runs when motor 24 is idle, thus preventing drive of the latter. When the press is idle and clearance motor 24 is running, the drive is through shaft 1I to clutch 10. Under this condition, clutch 10 is engaged to drive sprocket 12 clockwise. Chain 13 transmits driving power to shaft 3l to drive it in the clockwise direction. Due to the drive of shaft 3 I, chain 15 drives shaft 69 in the same direction, but chain 66 remains idle due to the fact that clutch 68 under such conditions is overrunning.

toi shaft 39 or cornerunitv 21 and on. another sprocket fixed toshaft, 3d: of; section joint 26y aords driveoi shaft. 3&1 Driving power is transmittect to shaft. 4 4!7 ofA section joint. 28 by means oi; endlesszchain 80,:runnine on. sprockets.; fixed.

to` shafts 3s and 44. Driving poweris transl- -niiizted from shaft 44 to.r theznext: succeeding-sec-y joint (not shown)- by meansK ot an endless chain 8| running: on a sprocket :fixed on shaft. and on. a sprocket iixed; on a shaft; oi such` succeeding section. joint. Shaft l|6v` ofv corner unit 29? is driven by an. endless` chain 82 runningon asprocket 83- fixed tor shaft 46 and` on a sprocket xed ony a shaftprecedingA section. ioint (not shown. Driving power is transmitted to shaft. I of section joint` 3d means of, an endless chain 84 running on sprockets xed on shafts 45 and 5|. Shaft 54` of end unit 53 is. driven by means o an endless chain; 851 running om 'a sprocket 8.6 fixed to shaft 5.4 xed to Shaft 5|.v

and onA a` sprocket The driveithus far described` is a conventional.v

type: of drive commonly used for driving` newspaper conveyors. Itwill be seen that whenever shaft 3|V is driven, which is always in the clockwisedirectionl that. shafts il, 39, 44, 46, 5| and 5A will be thus driven in` the same` direction.

through. the medium of the chain. and sprocket driving connections:` hereinbefore described. Shaft 3| through its geared connections with shafts 32 and- 34 of press` connection. unit 25, will afforddrive of such shafts in.` the. anti-clockwise direction. As` aforeindioated, each of the shafts 3,1, 39; 44, 46- andv 5.I have one toone ratio geared. driving connections with the shafts 38, 40, 45. 41, 52 and 5.5, respectively, and thus afford drive of thelast mentioned shafts in the anti clockwise direction.

The driving mechanism of the present conveyor system, besides being] aiorded drive from any one of the motors 21 22 or 21|, is. provided Vwith booster driving motors 8l and 88 as shown in Figs. 1 and 2. Motor 81 is provided with a.

shaft-81e on which is fixed a, sprocket 89. An

endless chain 90 running on sprocket 89v and; on, a. sprocket 9|y xed to shaft 44. of section joint 28 affords transmission of driving power from motor 87 to shaft 44. Motor 8B is provided with a shaft 88ai on which is fixed a sprocket 82. An

endless chain` 93- running on sprocket 92 and onv a sprocket 94 fixed to shaft 5| of section joint. 3|),l affords` transmission oi driving power from motor 88 to shaft 5|.v

Itis required that each of the motors 81 and 8.8- -bea three-phase alternating current motor of the so-called torque motor type. Generally considered the term torque motor indicates` a.

three-phase alternating current motor which develops maximum torque at standstill and which is. capable of applying stalled torque and operating at speeds `considerably below synchronous speed for relatively long periods of time without overheating or incurring injury. The

torque motor is usually designed in these respects to meet` operating requirements.

As suchA "torque motors are available in a wide variety of ratings, the selection of a desired size for such motors to meet the service conditions which motors 8T and 88v are called upon to meet is important. Whereas the present conveyor system is shown as having two jointz on a sprocket AIX; endlessfchairrkl: on. a sprocket iixedl veyor in empty condition and in. extreme loaded'A condition.`

("2)l The use of booster motors is desirableV when the driving torque load on the press foldershaft; in extreme loaded condition of the conveyor, appreciably exceeds. 650 pound-inches.V

(3) Maximum torquev output exerted Iby the booster motors, collectively, mustbe less than the. dri-ving torque required to-drive the conveyor in empty condition.

(4) Torque output of such booster motors should not vary greatly over the range of con. veyor i operating4 speeds.

As the main drive `of a newspaper conveyor during production operation ofthe printing pressv is derived from the press motors, the speed: of' the conveyor will depend upon the speed of the press. Usually the pulley shafts of the conveyor will run at speeds within a range of 0 to 16'0 Rf. P; M. Consequently, selection of a torque motor ldeveloping approximately 100 poundinches torque at R. P. M. hasy been found to be a good choice where it is desired to standardi'ze on a single sizemotor, which is adaptablev to a wide variety vof conveyor installations. Fig. 3v shows a curve A depicting the speed-torque characteristics of a commercially available torque motorwhi'chhas beenfou-nd to be a particularly suitable selection for the booster motorl service herein contemplated.

The location of such booster motors in the conveyork systemV is, to a certain extent, a matter of choice. In newspaper conveyors the drivingconnectionsy of such motors canl most readily be made with shafts o1 section joints. The ideal location and spacing of such motors can be determined from a consideration of the gradient of the torque required to drive the conveyor from the press connection end to the delivery table end under extreme loadedV condition of the conveyor.

It is required that booster motors 81 and 88 both be energized whenever one of the motors 2|, 22v or 24 is energized. Fig. 4 shows a control system whereby energization of motors 8'! and 38 is insured whenever one ofthe motors 2|, 22' or 24 is energized. More particularly, motor 81 is provided. with anelectromagnetic contactor 95 for effecting connection of the same to supply lines L1, L2 and L3 oia three-phase alternating current supply source. Similarly motor 88 is pro,- vi'dodwith an electromagnetic contactor 96'fo1 effecting its connection to supplyV lines L1, L2 and L3. Contactors 95. and 9S are provided with energizing windings 95a and Qta, respectively, which are energized whenever one of the motors 2|, 22 or 24 is energized. windings .95a and 96a are each connected at corresponding ends to line lL3 and their other ends are connected together to line L2, alternatively, through auxiliary contacts 91h of an electromagnetic contacter S1 associatedy with motor 24, through contacts 98' of an electromagnetic relay 98 associated with motor 2|, or through contacts 99h of an electromagnetic relay 99f associated with motor 22. 4

Motor 2| is provided with an electromagnetic contactor for effecting its connection to supply lines L1, L2 and L3 and motor 22 is provided with an electromagnetic contactor |0| for effecting its connection to lines L1, L2 and L3. Contactor |00 is provided with an energizing winding |00a whose energization is controlled by start and stop buttons |02, and |03, respectively. Further, contactor |00 is provided with auxiliary Contacts |00b for effecting a holding circuit connection for winding |00a and auxiliary contacts |||0c for controlling energization of an energizing winding 98EL of relay 98. Contactor |0| is provided with an energizing winding |0|a whose energization is controlled by start and stop buttons |04 and |05, respectively. Further, contacter |0| is provided with auxiliary contacts ||l|b for effecting a holding circuit connection for winding |0|a and auxiliary contacts |0|c for controlling the energization of an energizing winding 88a of relay 99,

Contactor 91 is provided with an energizing winding 91a whose energization is controlled by start and stop buttons |06 and |01, respectively. Further, contacter 91 is provided with auxiliary contacts 9'!c for effecting a holding circuit connection for winding 91a.

It will be apparent that whenever one of the motors 2|, 22 or 24 is energized by connection to lines L1, L2 and L3, through operation of its respective associated electromagnetic contacter, the windings 95*i and SI5a of contactors 95 and 95 will then be energized and such contactors will therefore effect connection of motors 81 and 88 to lines L1, L2 and L3, thereby insuring that the latter motors will run whenever one of the motors 2 22 or 24 are running.

If the booster motors 81 and 88 are properly selected with respect to torque output and the driving torque requirements of the conveyor system, these motors will then afford driving torque supplementing the driving torque afforded by the main driving motor and will run at a speed dictated by the speed of the main driving motor. In other words, these motors will be self-synchronizing in respect of speed and it is therefore unnecessary to provide speed synchronizing control. To insure such self-synchronization with respect to speed of booster motors 81 and 8B, the maximum torque output of these motors, collectively, must be less than the torque required to drive the conveyor in empty condition.

As will be appreciated, the use of booster motors 81 and 88 to afford supplemental driving torque, reduces the torque transmission load on press folder shaft Ha, the driving connections between shaft ||a vand shaft 3| of the conveyor, shafts 3|, 31 and 39 of the conveyor, and at the same time tends to equalize the torque transmission load on all shafts of the conveyor proper.

Referring to Fig. 2, spring biased idler rollers |08 and |09 are provided for the endless chains 80 and 84, respectively, to regulate the slack in these chains. When the conveyor is started from rest, booster motors 8'| and 88 will be energized concurrently with whichever main driving motor is selected for driving the conveyor. Consequently, motors 8'| and 88 will pick up the drive of shafts 44 and 5| before the effect of the drive of the main driving motor is transmitted thereto. Thus for a short interval, chains 80 and 84 will respectively be tight on the sides opposite the idler rollers |08 and |09, and will be slack on the sides adjacent these idler rollers. When the effect of the main driving motor reaches these chains, a reversal takes place in the tight and slack sides of chains and 84 with the sides adjacent idler rollers |08 and |00 then becoming tight and the sides opposite becoming slack. The idler rollers |00 and |09 suppress the tendency of chains 80 and 84 to whip during the sudden reversal in their tight and slack sides which, if uncontrolled, might cause such chains to jump their end sprockets or cause them to break. Preferably, spring biased idler rollers or sprockets shouldbe used in conjunction with each of the main driving chains immediately to the press connection side of each booster motor.

While the drive system herein shown and described is particularly advantageous for use in connection with newspaper conveyors, it will be apparent to those skilled in the art that such drive system is not limited to use with conveyors of this type but can be adapted for use in connection with conveyors of other types.

I claim;

l. The combination with a conveyor which when driven affords transport of materialsin a continuous manner from. one point to another, a drive mechanism for said conveyor comprising a plurality of shafts in a spaced apart relation along the traverse of said conveyor to afford drive of said conveyor at a plurality of points and means interconnecting said shafts for transmitting driving power therebetween in train, a prime mover, and driving connections between said prime mover and said drive mechanism, said prime mover when energized supplying said drive mechanism with driving power, of an alternating current torque motor, driving connections between said torque motor and a shaft of said drive' mechanism, said torque motor having speedtorque characteristics such that it is incapable of driving said conveyor alone under any conditions, but rendering it self-synchronizing as to speed so that when energized it inherently supplies supplemental driving torque to said drive mechanism at the same speed as that afforded the latter by said prime mover, and means affording supply of electrical power to said torque motor whenever said prime mover is supplying driv-` ing power to said drive mechanism.

2. The combination. with a conveyor which when driven affords transport of materials in a continuous manner from one point to another,`

a drive mechanism for said conveyor comprising a plurality of shafts in a spaced apart relation along the traverse of said conveyor to afford drive of said conveyor at a plurality of points and means interconnecting said shafts for transmitting driving power therebetweenV in train, a. prime mover, and driving connections between said prime mover and said drive mechanism, said prime mover when energized supplying said drive mechanism with driving power, of an alternating current torque motor, driving connections between said torque motor and a shaft of said drive mechanism, said torque motor having speed-torque characteristics such that itl is incapable of driving said conveyor alone under any conditions, but rendering it self-synchronizing as to speed so that when energized it inherently supplies supplemental driving torque to said drive mechanism at the same speed as that afforded the latter by said prime mover to thereby reduce the torque `transmission load on the first mentioned driving connections and all shafts of said drive mechanism lying between said first mentioned driving connections and the shaft with which said torque motor has connection,

is supplying driving power to said drive mechanism.

3. The combination with a conveyor which when driven affords transport of materials in a continuous manner from one point to another, a drive mechanism for conveyor comprising a plurality of shafts in a spaced apart relation along the traverse length of conveyor to afford drive of the latter at a plurality of points and means interconnecting said shafts for transmission of driving power therebetween in train, an electric motor, and driving connections between said motor and one shaft oi said drive mechanism, said motor when energized supplying driving power to Said drive mechanism, of an alternating current torque motor, driving connections between said torque motor and another shaft of said drive mechanism, said torque motor having speed-torque characteristics such that it is incapable of driving said conve-yor alone under any conditions, but rendering it self-synchronizing as to speed so that when energized it inherently supplies supplemental driving torque to said drive mechanism at the same speed as that afforded the latter by the first mentioned electric motor toI thereby reduce the torque transmission load on the first mentioned driving connections, said one shaft and such of the other shafts of said drive mechanism as lie between said one and said other shaft, and means affording supply of electrical power to said torque motor whenever said rst mentioned motor is supplying driving power to said drive mechanism.

4. In combination, a conveyor which when driven affords transport of materials in a continuous manner from one point to another, a drive mechanism for said conveyor comprising a plurality of shafts in spaced apart relation along the traverse of said conveyor to afford drive of the latter at a plurality of points, sprockets fixed on said shafts, and endless chains running between adjacent shafts on said sprockets, an electric motor, driving connections between said motor and one shaft of said drive mechanism, said motor when energized supplying driving power to said drive mechanism, an alternating current torque motor, driving connections between said torque motor and another shaft of said drive mechanism, said torque motor having speedtorque characteristics such that it is incapable of driving said conveyor alone under any conditions, but rendering it self-synchronizing as to speed so that when energized it inherently supplies supplemental driving torque to said drive mechanism at the same speed as that afforded the latter by the first mentioned electric motor to thereby reduce the torque transmission load on the first mentioned driving connection and all shafts of said drive mechanism lying between said rst mentioned driving connections and said other shaft, and means affording supply of electrical power to said torque motor whenever said first mentioned electric motor is supplying driving power to said drive mechanism.

5. In combination, a conveyor which when driven affords transport of materials in a continuous manner from one point to another, a drive mechanism for said conveyor comprising a plurality of shafts in spaced apart relation along the traverse of said conveyor to afford drive of the latter at a plurality of points, sprockets fixed on said shafts, and endless chains running between adjacent shafts on said sprockets, an electric ino-tor, driving connections between said motor and one shaft. of said drive mechanism, said motor when energized supplying driving power to said drive mechanism, an alternating current torque motor, driving connections between said torque motor and another shaft of said drive mechanism, said torque motor having speedtorque characteristics such that it is incapable of driving said conveyor alone under any conditions, but rendering it self-synchronizing as to speed so that when energized it inherently supplies supplemental driving torque to said drive mechanisni at the same speed as that aiorded the latter 'oy first mentioned electricmotor to thereby reduce the torque transmission load on the first mentioned driving connections and all shafts of the drive mechanism between said nrst mentioned driving connections and said other shaft, means affording supply of electrical power to said torque motor whenever said first mentioned electric motor is supplying driving pover to said drive mechanism, and spring biased idler sprocket engaging the endless chain running between said other shaft and the shaft lying immediately to the side toward said irst mentioned driving connections for damping the effect of shock forces occurring in such chain as an incident to reversals in tight and slack sides thereof.

6. The combination with a conveyor which when driven aords transport of materials in a continuous manner from one point to another, a drive mechanism for said conveyor comprising a plurality of shafts in` a spaced apart relation along the traverse length of said conveyor to aiord drive of the latter at a plurality of points and means interconnecting said shafts for transmission of driving power therebetween in train, an electric motor, and driving connections between said motor and one shaft of said drive mechanism, said motor when energized supplying driving power to said drive mechanism, of a plurality of alternating current torque motors individualized respectively to other shafts of said drive mechanism, driving connections between each of said torque motors and their respective associated shafts, said torque motors each having speed-torque characteristics such that they are incapable, individually or collectively, of driving said conveyor alone under any conditions, but rendering each self-synchronizing as to speed so that when energized they each inherently supply supplemental driving torque to said drive mechanism at the same speed as that aiforded the latter by the rst mentioned motor, and means affording supply of electrical power to said torque motors whenever said rst mentioned motor is supplying driving power to said drive mechanism.

THEODORE B. JOCHEM.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,888,369 Cramer Nov. 22, 1932 2,215,647 Lightfoot Sept. 24, 1940 2,428,567 Harris et al. Oct. 7, 1947 

